Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

The possibility of functionalization of dipyrido[3,2-e:2′,3′-h]acenaphthene containing a quino[7,8-h]quinoline fragment and being a highly basic diazine analog of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) has been studied for the first time. In addition to the pronounced tendency of the title compound to form associates with an intramolecular hydrogen bond of the NHN type (new examples with the participation of pyridine rings, including self-associates are shown) and its inertness to amination reactions of the pyridine rings, the naphthalene core at positions 5(8) and the CH2CH2 bridge (dehydrogenation) undergo chemical modifications under mild conditions, giving the corresponding acenaphthylenes. The latter can also be obtained in an unusual way by tele-elimination from 5,8-dibromodipyridoacenaphthene by reaction with neutral or anionic bases.


Experimental data
1 H and 13 C NMR spectra were recorded on a Bruker DPX-250 (250 MHz) spectrometer with the solvent residual peaks as the internal standard.The HR-ESI mass spectra were obtained on a Bruker maXis spectrometer equipped with an electrospray ionization (ESI) source; methanol was used as the solvent.The instrument was operated in the positive mode using an m/z range of 50-1200.The capillary voltage of the ion source was set at 4000 V.The nebulizer gas pressure was 1.0 bar, and the drying gas flow was set to 4.0 L/min.Dipyridoacenaphthene 5 was prepared according to the published procedure.S4 Light-yellow crystals, mp 230-232 °C (decomp.).The crystals, yellowish prisms, suitable for XRD measurements were obtained from acetonitrile.
Proton and molecular complexes (5•HX) were prepared by mixing equimolar amounts of base 5 and the corresponding acid (1 equivalent in the case of aqueous HBF 4 or 0.5 equivalents in the case of 4,6-dichlororesorcinol) in a minimum volume of acetonitrile followed by 5-fold dilution with Et 2 O.The residue thus formed was washed with Et 2 O, vacuum dried and recrystallized to give the desired salt almost quantitatively.The solvent was CHCl 3 in the case of 4,6dichlororesorcinol followed by evaporation of the clear solution to dryness.
Tetrafluoroborate 5•HBF4.Pale-yellow crystals, darken above 300 °C.For spectral and analytical data see ref. S4 The crystals, yellowish needles, suitable for XRD measurements were obtained from acetonitrile.
Chloride dihydrate 5•HCl•2H2O.The compound was occasionally obtained from a 1:1 mixture of 5 and chloranil on evaporation of its acetonitrile solution in air at ambient temperature.Small S5 pale-yellow crystals, darken above 290 °C.The crystals, pale-yellow needles, suitable for XRD measurements were obtained from acetonitrile.Route 2. A mixture of compound 10 (20 mg, 0.06 mmol) and chloranil (25 mg, 0.10 mmol) in CHCl 3 (5 mL) was refluxed for 1 h in darkness.The solvent was evaporated, and the crude product was purified by column chromatography (Al 2 O 3 , CHCl 3 ) to give 12 (7 mg, 33%) with the properties identical to those of the sample prepared by Route 1.

Table S2 :
Dehydrogenation Thin layer chromatography was carried out on Al 2 O 3 and on silica gel (70-230 mesh, Aldrich).The progress of reactions and the purity of products were monitored by TLC on Al 2 O 3 ; development with iodine vapor or UV-light.The melting points were measured in sealed capillaries and are uncorrected.The solvents were purified and dried by standard methods.

data of pure and intermediate compounds
S9Spectral